Freecutting v Tempered EN16 & EN8 – How do they differ?

[Steve WithnellParticipant @stevewithnell34426]

I've just picked up some EN8M and EN16M bar stock which is of the free-cutting type. Used for things like IC engine cylinders and camshafts, how do these compare against the EN8T/EN16T versions?

I'm hoping the 'M' steel is easier to machine than the 'T', without trading away too much by way of resistance to wear, particularly when used for cams.

Regards

Steve

[Steve WithnellParticipant @stevewithnell34426]

[Mark RandParticipant @markrand96270]

T is the heat treat condition rather than a chemical variation. Usually about 30HRC, which actually makes the metal slightly nicer to machine:- less 'grabby', compared with the straight EN8 or EN16. It's also a reasonable state for components that don't suffer extreme stress. Nuts come to mind.

The M versions have extra sulphur to make them easier to machine, but they won't be hardened as they come. Doesn't matter for cams if you're going to harden them after machining.

[Steve WithnellParticipant @stevewithnell34426]

Hmmm, I was going to harden the cams, but not the cylinders as they are much more likely to distort. At the end of the day, I'm more likely to run the engines for 10's of hours rather than 1000's.

Steve

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